Electronic signs are becoming popular in retail stores in order to keep pricing and sale information as current as possible. For example, prices can be kept up-to-date without having to reprint and dispose of paper pricing sheets whenever there is a sale or price change. The retailer can electronically write the information to a thin, flexible bi-stable sheet of prepared media and use it as a drop in replacement for a paper sign in their current signage holders. The customer benefits by having clear up-to-date information they need about the product, and the retailer benefits by having programmable information that can be readily changed and rewritten by electronic means.
One example of an electronic sign as discussed above is described in WO 03/083561 A2, which discloses an electronically programmable/controllable sign including multilayer displays for retail signage. The displays are fabricated with bi-stable material such as cholesteric liquid crystal material, which can maintain a viewable state indefinitely in the absence of power. The sign is permanently connected to a programmer/controller and drivers.
Another example of an electronic sign is described in WO 03/083613 A2. It discloses a system including low power electronic signs, a remote location managing system for communicating with the plurality of signs, and means of wireless communication to said signs via a computer network connected to a server computer. The system utilizes the advantage of a bi-stable display by using a power source only when necessary to change the state of the display.
One problem with the signage systems described in the above publications is the cost involved in fitting a complete retail store with multiple, fully integrated signs, wherein each sign includes electronics, a power source, and encasements or frames. Most retail stores have hundreds of pricing signs throughout the store. Most of these signs need price changes once a week or less. It may not be economical to purchase a system such as those described above when many of the signs do not require frequent updates.
Another problem with the systems described above is that the signs include the electronics and power source, and are a costly substitute for paper signs, which is what they are often replacing. Because of the added thickness of the electronic signs caused by the electronics and power source, the signs can be difficult to mount on item racks and in holders pre-existing in stores for paper signs. These systems fail to offer a simple, cost effective way to stock a retail store with affordable, rewritable signs, which fit more closely with a retailer's current pricing scheme.
One method of providing a more cost effective system is set forth in U.S. patent application Ser. No. 10/851,907 to Capurso et al., filed May 21, 2004, wherein bistable displays, capable of displaying information in the absence of power, are coupled with one or more powered display stands or independent writers capable of writing information to each display individually. This system allows frequently changed displays to be in a powered display holder, while infrequently updated displays can be rewritten by removal and placement in a writer.
The difficulty in using a separate writer from the display occurs in aligning the electrical connections of the display with those of the writer such that the display can be properly written every time. In order to achieve the best appearance for customer readability on bi-stable displays, finer resolutions (pixels per inch) are essential, meaning that electrical connections are closely spaced. Due to manufacturing errors, or different manufacturers' tolerances, each display can potentially have a slightly different arrangement of electrical connections, making writing of all displays with one writer difficult.
In manufacturing, it is known to provide some means of alignments between layers of a display for accuracy in manufacture and repeatability. For example, perforations can be used in film transportation operations, as disclosed in U.S. Pat. Nos. 6,269,225 and 6,424,387 to Sato. The use of the perforations allows control over film movement throughout processing, minimizing alignment error.
Various means of aligning electrical connections are known in the art. For example, U.S. Patent Application Publication No. US 2003/0021541 A1 refers to micro-replicated male and female features of optical devices for alignment of the device with a die. U.S. Patent Application Publication No. US 2003/0128080 A1 teaches male-female mechanical features aligning with a circuit board. U.S. Pat. No. 4,808,112 discloses the use of anisotropic adhesive to fix two flexible circuits together, and uses male/female features to promote alignment of the circuits. These aforementioned publications however refer to permanently mounting substrates to another substrate or circuit board.
There is therefore a need for a rewritable bi-stable display system in which a display can be accurately aligned for writing in a writing device and removed from the writing device for use in retail signage.